Apparatus for recycling asphalt materials

Abstract: Apparatus for processing recyclable asphalt material includes an elongate drum (12) having a generally cylindrical wall (14), a central axis (c), a first end (18) and a second end (16), and being mounted for rotation about the central axis (c), with the central axis tilted at an acute angle (A) so as to elevate one of the first and second ends relative to the other of the first and second ends, a heating chamber (30) adjacent the first end (18) of the drum, a plurality of breaker members (50) arrayed generally parallel to the central axis (c) of the drum and placed within the drum, a heat conduit (58) extending along the drum coaxial with the breaker members, a heating arrangement (40) for supplying heat to the heating chamber (30), ducting interconnecting the heating (30) chamber, the breaker members (50), and the heat conduit serially such that heat from the heating chamber is conducted from adjacent the first end (18) of the drum to adjacent the second end (16) of the drum and is returned to adjacent the first end of the drum serially through the breaker members and the heat conduit, a feed arrangement (70) for feeding the recyclable asphalt material into the drum, adjacent the elevated one of the first and second ends of the drum, and a rotational drive (22) for rotating the drum, the breaker members and the heat conduit about the central axis so as to tumble the recyclable asphalt material within the drum, against the breaker members and against the heat conduit to process and deliver the desired recycled asphalt material adjacent the other of the first and second ends of the drum.

Description: The present invention relates generally to the processing of asphalt materials and pertains, more specifically, to recycling existing asphalt pavement materials. Asphalt has long been the material of choice for pavement and has found widespread use throughout the world in filling the need for more and more pavement. More recently, recycled asphalt products are being specified for use in an effort to conserve materials used in asphalt production. The use of recycled asphalt materials has become more important as existing pavement is reconditioned or replaced and the disposal of the old, replaced pavement material becomes more difficult and more costly. As a result, large amounts of old asphalt material have become available for reuse; however, current practices have limited such reuse to crushing the relatively large pieces of old asphalt materials, as received from the field, and then mixing the crushed, reduced-size recyclable asphalt material with new material. The mixing of recyclable asphalt material with virgin asphalt has led to unstable reactions, produces unwanted amounts of pollutants, and thus severely limits the use of recyclable asphalt materials. Five basic methods currently are in use for the utilization of recyclable asphalt. In the weigh-hopper method, uncoated virgin aggregate is superheated and then added to recyclable asphalt material in a hopper where heat is transferred quite rapidly from the heated aggregate to the recyclable asphalt material. The result is a tendency toward an unstable reaction at the point of blending, limiting the amount of recyclable asphalt material which can be introduced. In the batch plant bucket elevator method, recyclable asphalt material is metered into a bucket elevator where heat transfer takes place. Again, the percentage of recyclable asphalt material must be limited in order to preclude the emission of excessive pollutants. Another method uses a parallel-flow drum mixer in which virgin aggregates are introduced at the burner end of a drum and are superheated. Recyclable asphalt material is introduced downstream, adjacent the center of the drum, where the recyclable asphalt material is mixed with the superheated virgin aggregate and hot gases. The exposure of fine recyclable asphalt material to the superheated aggregate and hot gases causes a rapid flash-off and the emission of "blue-smoke", a highly undesirable pollutant, in addition to other hydrocarbon emissions. These emissions must be controlled, resulting in strict limitations on the amounts of recyclable asphalt products introduced by the method. In a similar procedure, a separate mixing chamber is used in connection with a parallel-flow drum mixer so that the recyclable asphalt materials are mixed with heated aggregate outside the hot gas stream in the drum. The method enables the introduction of greater amounts of recyclable asphalt materials without the creation of blue-smoke, but hydrocarbon emissions must still be contended with. The use of a counter-flow drum mixer with a separate mixing chamber, wherein the location of the burner is reversed so that virgin material moves toward the burner while exhaust gases move in the opposite direction, constitutes another improvement in that even more recyclable asphalt material can be mixed with virgin material; however, the amount of recyclable asphalt material must still be limited in order to control the emission of pollutants. All of the above-outlined methods usually require a separate scrubber and screening apparatus for sizing the recyclable asphalt material prior to introducing the material into the mix with virgin aggregate. United States Patent US-A-5188299 discloses an apparatus for processing recyclable asphalt material received from the field in relatively large pieces for delivery in a mass containing desired smaller aggregate-sized pieces for reuse, the apparatus comprising: an elongate drum having a generally cylindrical wall, a central axis, an inlet end and an outlet end; mounting means for mounting the drum with the central axis tilted at an acute angle so as to elevate the inlet end relative to the outlet end; a heating chamber adjacent the outlet end of the drum and extending along the drum toward the inlet end over a first axial portion of the drum, the heating chamber having an interior; a plurality of breaker members connected to the heating chamber for the conduction of heat from the heating chamber to the breaker members, the breaker members being tubular and extending from the heating chamber along a second axial portion of the drum toward the inlet end of the drum, each breaker member having an interior extending along the axial length of the breaker member and each interior being in communication with the interior of the heating chamber, the breaker members being arrayed generally parallel to the central axis of the drum and placed between the central axis and the wall of the drum, the breaker members being spaced from one another circumferentially about the drum to establish a cage-like assembly between the central axis and the wall of the drum, the circumferential spacing between adjacent breaker members being selected such that only the desired smaller aggregate-sized recyclable asphalt material will pass between adjacent breaker members; heating means for supplying heat to the interior of the heating chamber, such that the heat is conducted to the breaker members connected to the heating chamber; feed means for feeding the large pieces of recyclable asphalt material received from the field into the cage-like assembly established by the breaker members, adjacent the inlet end of the drum; and rotational means for rotating the drum, and the breaker members therein, about the central axis so as to tumble the large pieces of recyclable asphalt within the heated cage-like assembly, thereby simultaneously reducing the size of the relatively large pieces to the desired aggregate-sized pieces and heating the mass containing the desired aggregate-sized pieces, which mass passes radially between the breaker members to proceed toward the outlet end for delivery at the outlet end of the drum. The present invention provides apparatus which avoids many of the problems encountered in the above-outlined apparatus and methods and exhibits several objects and advantages, some of which may be summarized as follows: eliminates the need for preliminary crushing and screening of recyclable asphalt materials received from the field, and the equipment needed for such preliminary crushing and screening; precludes direct contact between the recyclable asphalt materials and any open flame or hot gases, thereby eliminating a potential source of pollutants, and especially "blue-smoke" and hydrocarbon emissions; effectively recycles used asphalt materials for-use either in a mix containing a very high percentage of recycled product with virgin aggregate and asphalt, or one-hundred percent recycled materials; provides apparatus which is relatively compact and even more portable than before for ready transportation and use directly at a wider variety of project sites; enables increased versatility in complementing existing asphalt plants for the use of recycled asphalt product; provides an environmentally sound approach to the conservation of asphalt products at minimal cost; eliminates the need for disposal of used asphalt materials; effectively deals with pollutants which emanate from the asphalt materials being processed for reuse; and enables the practical processing of recyclable asphalt materials for widespread use with efficiency and reliability. The present invention provides an apparatus for processing recyclable asphalt material received from the field in relatively large pieces for delivery in a mass containing desired smaller aggregate-sized pieces for reuse, the apparatus comprising: an elongate drum having a generally cylindrical wall, a central axis, a first end and a second end, the cylindrical wall including an inner surface and an outer surface; mounting means for mounting the drum for rotation about the central axis, with the central axis tilted at an acute angle so as to elevate one of the first and second ends relative to the other of the first and second ends; a heating chamber adjacent the first end of the drum, the heating chamber having an interior; a plurality of breaker members, the breaker members being tubular and extending along the drum between the first and second ends of the drum, the breaker members being arrayed generally parallel to the central axis of the drum and placed between the central axis and the wall of the drum; a heat conduit extending along the drum between the first and second ends of the drum, the heat conduit being coaxial with the breaker members; heating means for supplying heat to the interior of the heating chamber; ducting means interconnecting the interior of the heating chamber, the breaker members, and the heat conduit such that heat from the interior of the heating chamber is conducted from adjacent the first end of the drum to adjacent the second end of the drum and is returned to adjacent the first end of the drum through the breaker members and the heat conduit; feed means for feeding the large pieces of recyclable asphalt material received from the field into the drum, adjacent the elevated one of the first and second ends of the drum; and rotational means for rotating the drum, the breaker members and the heat conduit about the central axis so as to tumble the large pieces of recyclable asphalt material within the drum, against the breaker members and against the heat conduit, thereby simultaneously reducing the size of the relatively large pieces to the desired aggregate-sized pieces and heating the mass containing the desired aggregate-sized pieces, which mass proceeds toward the other of the first and second ends of the drum for delivery from the drum ; characterized in that the heating chamber communicates with the heat conduit adjacent the first end of the drum and the breaker members communicate with the heat conduit adjacent the second end of the drum, such that the heat is conducted serially from the heating chamber, through the heat conduit and then through the breaker members to be exhausted from the breaker members adjacent the first end of the drum. For a better understanding of the heat circuit of the present invention, wherein heat is conducted serially from the heating chamber, through the heat conduit and then through the breaker members to be exhausted from the breaker members adjacent the first end of the drum, and to show how the same may be carried into effect, reference will now be made, by way of example, to Figures 6 to 10 of the accompanying drawings, whereas Figures 1 to 5 of the drawings show different heat circuits not within the scope of the present invention. However, Figures 1 to 5 show auxiliary features which can be adopted as preferred features in the apparatus of the present invention illustrated in Figures 6 to 10 of the drawings. In the drawings : - FIG. 1 is a pictorial view of an apparatus which utilizes a heat circuit constructed in accordance with the disclosure of US-A-5188299 and incorporates an auxiliary feature of the present invention; FIG. 2 is a somewhat diagrammatic, longitudinal cross-sectional view of the apparatus of FIG. 1; FIG. 3 is a fragmentary pictorial view showing still another apparatus; FIG. 4 is a diagrammatic, longitudinal cross-sectional view of another apparatus which utilizes a heat circuit constructed in accordance with the disclosure of US-A-5188299 and which incorporates another auxiliary feature of the present invention; FIG. 5 is an enlarged fragmentary cross-sectional view taken along line V - V of FIG. 4; FIG. 6 is a diagrammatic, longitudinal cross-sectional view of an apparatus constructed in accordance with the present invention illustrating one embodiment of the present invention; FIG. 7 is a diagrammatic, longitudinal cross-sectional view of another apparatus constructed in accordance with the present invention illustrating yet another embodiment of the invention; FIG. 8 is a diagrammatic enlarged fragmentary cross-sectional view taken along line VIII-VIII of FIG. 7; FIG. 9 is a diagrammatic enlarged fragmentary cross-sectional view similar to FIG. 8, but showing another embodiment of the present invention; and FIG. 10 is a diagrammatic, longitudinal cross-sectional view of another apparatus constructed in accordance with the present invention illustrating yet a further embodiment of the invention. Referring to FIGS. 1 and 2, and apparatus which utilizes an auxiliary feature of the present invention in conjunction with a heat circuit which is the subject of US-A-5188299 is illustrated in the form of apparatus 200 which is seen to include an elongate drum 212 having a generally cylindrical wall 214 and an interior 215 extending axially between an inlet end 216 and an outlet end 218. Drum 212 is mounted upon a platform 220 for rotation about a central axis CC by means of roller assemblies 222 placed on a base 223 on the platform 220 and engaging corresponding circumferential tracks 224 carried by the drum 212, and electric motors 226 drive the roller assemblies 222. Alternately, a separate chain-and-sprocket drive may couple the electric motors 226 with the drum 212. The base 223 is inclined so that the inlet end 216 of the drum 212 is elevated relative to the outlet end 218. The angle of inclination is maintained relatively shallow, typically at about three to six degrees, and is adjustable. A heating chamber 230 is located adjacent the outlet end 218 of the interior 215 of the drum 212 and includes a cylindrical side wall 232 which extends along the drum 212 toward the inlet end 216 over a first axial portion of drum 212 from an inlet end 234 of the heating chamber 230 to a front wall 236. A burner 240 is located outside the heating chamber 230 and projects toward the interior 242 of the heating chamber 230 to provide a heating flame 244 projecting toward the interior 242 of the heating chamber 230. A baffle 246 is provided at the front wall 236. A plurality of breaker members in the form of tubular members 250 extend axially, along a second axial portion of drum 212, between the heating chamber 230 and the inlet end 216 of the interior 215 of the drum 212, generally parallel to the central axis CC, and are arrayed circumferentially about the central axis CC. The tubular members 250 are assembled into a cage-like assembly 252 which is supported within the drum 212 by support rings 254 and struts 256. Each tubular member 250 has an interior 258 which extends axially along the length of the tubular member 250. Headers in the form of manifolds 260 are integral with the ends of the tubular members 250 adjacent the heating chamber 230, and the manifolds 260 are integral with the front wall 236 of the heating chamber 230 to connect the tubular members 250 with the heating chamber 230. As before, two tubular members 250 are connected to each manifold 260 and each manifold 260 has a single leg 262 connected to the front wall 236 of the heating chamber 230. The interior 258 of each tubular member 250 communicates with the interior 242 of the heating chamber 230 through the interior 264 of each corresponding manifold 260 so that hot gases in the heating chamber 230 pass through the manifolds 260 and into the tubular members 250. Recyclable asphalt material is received from the field in relatively large pieces 270, usually in chunks spanning about one foot across and is fed directly into apparatus 200, as seen at 271. The large pieces 270 are fed by an infeed conveyor 272 through the inlet end 216 of the interior 215 of drum 212 and into the cage-like assembly 252 established by the array of tubular members 250. As the drum 212 is rotated, the cage-like assembly 252 also rotates about the central axis CC and the large pieces 270 are tumbled within the cage-like assembly 252 and simultaneously are broken up and heated by contact with the tubular members 250 of the cage-like assembly 252 as the recyclable asphalt material proceeds downstream from the inlet end 216 toward the outlet end 218 of the interior 215 of drum 212. The circumferential spacing between adjacent tubular members 250 is selected so that upon reaching the desired aggregate-size, the recyclable asphalt material 276 will drop out of the cage-like assembly 252, and fall to wall 214 of the drum 212, all as described above in connection with apparatus 10. The desired aggregate-sized recyclable asphalt material 276 continues down the wall 214 of the drum 212, assisted by flights 280 affixed to the wall 214, until the material 276 reaches the outlet end 218 of the interior 215 of the drum 212. In addition, material 276 is tumbled onto the side wall 232 of the heating chamber 230 where additional heat is transferred to the material 276 and further flights 282 affixed to side wall 232 assist in moving the material 276 downstream. The legs 262 of the manifolds 260 are spaced apart circumferentially a distance greater than the spacing between the tubular members 250. Thus, intermediate-sized pieces 288 of recyclable asphalt material which now are smaller than pieces 270, but still remain larger than that which is permitted to fall through the spacing between the tubular members 250, will fall between the legs 262 to enter the mass of material in the stream 290 of asphalt material leaving the drum 212. After leaving the drum 212, the stream 290 is passed through a screen 292 where the intermediate-sized pieces 288 are separated and transferred to a back feed conveyor 294. Back feed conveyor 294 delivers the intermediate-sized pieces 288 to a bin 296, and an elevator 298 moves the intermediate-sized pieces 288 from the bin 296 to the infeed conveyor 272 for return to the drum 212. The stream 290 of desired aggregate-sized pieces of material 276 is delivered through an exit chute to an outfeed conveyor. In the preferred configuration, wall 214 of drum 212 is comprised of an inner wall 302 and an outer wall 304, with an annular heat chamber 306 between the inner wall 302 and the outer wall 304. Return members in the form of elbows 308 are connected between the end 310 of each tubular member 250 and the annular heat chamber 306 so that the heated gases which pass from the heating chamber 230 through the tubular members 250 are directed into the annular heat chamber 306 to flow through the wall 214 of the drum 212 and further heat the wall 214 as the heated gases are passed downstream. In this manner heat is conserved and more heat is made available for the process. An insulating jacket 314 extends circumferentially around the drum 212 to further conserve heat, as explained in United States patent US-A-4,932,863. It is noted that at no time is the recyclable asphalt material exposed to direct flame. Moreover, introduction of the recyclable asphalt material at the inlet end 216, remote from the heating chamber 230, presents the recyclable asphalt material at the lower temperature end of the drum 212, and the temperature is raised gradually as the material progresses toward the outlet end 218, thereby reducing any tendency toward generating excessive harmful pollutants. However, any harmful pollutants which may be generated in the interior 215 of the drum 212 during the process is dealt with in apparatus 200, as described below. Volatile pollutants which emanate from the recyclable asphalt material as the process is being carried out in the apparatus 200 are dealt with by oxidizing the pollutants in a volatile organic compound oxidation device 320. To that end, the volatile pollutants are conducted from the interior 215 of the drum 212 to the volatile organic compound oxidation device 320 by gas conduction means shown in the form of a manifold 322 located adjacent the outlet end 218 of the interior 215 of the drum 212 and a duct 324 extending between and communicating with the manifold 322 and a plenum chamber 326 extending around the outer periphery of the volatile organic compound oxidation device 320 at the inlet end 328 of the volatile organic compound oxidation device 320. A fan 330 draws the volatile pollutants from the interior 215 of the drum 212, through the manifold 322 and duct 324, and forces the volatile pollutants into the plenum chamber 326, to pass through openings 332 into the volatile organic compound oxidation device 320. The volatile organic compound oxidation device 320 is a device of a type well known in the art of pollution control and operates in response to heat to oxidize the volatile pollutants delivered from the interior 215 of the drum 212. By interposing the device 320 between the burner 240 and the heating chamber 230, the burner 240 provides the heat necessary to operate the device 320, thus rendering the use of the device 320 economical and practical. Upon oxidation of the pollutants in the device 320, additional heat is produced by the oxidation reaction. Should the heat become too intense for safe introduction into the heating chamber 230, cooling means interposed between the volatile organic compound oxidation device 320 and the heating chamber 230 is employed to reduce the temperature between the outlet 336 of the volatile organic compound oxidation device 320 and the interior 242 of the heating chamber 230. Thus, air distribution means in the form of a plenum 340 is placed on the volatile organic compound oxidation device 320 so as to be located adjacent the inlet end 234 of the heating chamber 230 and communicate with the interior 242 of the heating chamber 230 through apertures 342. A blower 344 forces ambient air into the plenum 340 to be distributed into the volatile organic compound oxidation device 320 and to the interior 242 of the heating chamber 230 for reducing the temperature at the inlet end 234 of the heating chamber 230. Alternately, the plenum 340 may be placed on the heating chamber 230 itself, adjacent the inlet end 234 of the heating chamber 230 and the outlet 336 of the volatile organic compound oxidation device 320, rather than on the volatile organic compound oxidation device 320, for reducing the temperature at the inlet end 234 of the heating chamber 230. In either arrangement, the cooling means is interposed between the volatile organic compound oxidation device 320 and the heating chamber 230 for distributing ambient air to the interior of the heating chamber 230 to reduce the temperature at the inlet end 234 of the heating chamber 230. When use of the apparatus 200 is to be discontinued, there is a gradual slow-down in production in the drum 212, requiring lowered heat to the tubular members 250; however, full heat must be maintained in the volatile organic compound oxidation device 320 for continued appropriate operation during the transition from full operation to full shut-down. Accordingly, heat is bypassed by the opening of a damper 350 located adjacent the outlet 336 of the volatile organic compound oxidation device 320, which damper 350 is opened to vent excess heat through a stack 354 in order to bypass heat from the volatile organic compound oxidation device 320 away from the heating chamber 230 and thereby protect the component parts of the apparatus 200 against excessively high temperatures during cool down. As a further measure of protection against the effects of excessive heat, it is preferable to construct the heating chamber 230, the manifolds 260 and at least the portions of the tubular members 250 located adjacent the manifolds 260 and the heating chamber 230, of a heat and corrosion resistant alloy, such as stainless steel. Residual emissions and steam emanating from the inlet end 216 of the interior 215 of the drum 212 are collected by means shown in the form of an auxiliary hood 360 placed adjacent the inlet end 216. A duct 362 communicates with the hood 360 and provides a passage to an auxiliary stack 364 within which an exhaust fan 366 operates to exhaust the emissions and steam collected in the hood 360. The heated gases exhausted from the tubular members 250 also are passed into the auxiliary stack 364, as seen at 368, to be exhausted to the atmosphere. Alternately, should the residual emissions contain excessive pollutants, duct 362 may be routed to plenum 340, instead of to auxiliary stack 364. In order to enhance the portability and versatility of the apparatus 200, as well as enable ready access to the interior 242 of the heating chamber 230 for cleaning and maintenance, the burner 240 and the volatile organic compound oxidation device 320 are selectively detached from the heating chamber 230 by coupling means which enable the selective translation of the burner 240 and the volatile organic compound oxidizing device 320 into and out of coupled engagement with the heating chamber 230. Thus, the burner 240 is mounted upon a wheeled carriage 370 which, in turn, is placed upon tracks 372 extending longitudinally essentially parallel to the central axis CC of the drum 212. Likewise, the volatile organic compound oxidizing device 320 is mounted on a wheeled carriage 374 which, in turn, is placed upon the tracks 372. The burner 240 and the device 320 are selectively translated along the tracks 372 in the direction 380 away from the drum 212 in order to retract and uncouple the burner 240 and the device 320 from the heating chamber 230 to expose the interior 242 of the heating chamber 230. The burner 240 and the device 320 are advanced, by translation along the tracks 372 in the direction 382, so as to telescopically engage the volatile organic compound oxidation device 320 and the heating chamber 230 to couple the burner 240 and the device 320 with the heating chamber 230 for operation of the apparatus 200. The tracks 372 are supported on a frame 384 of a smaller trailer 386 having a carriage 388 for transport independent of the truck trailer 390 upon which the drum 212 is carried. A winch 392 is mounted upon the frame 384 of the trailer 386 and is coupled with the tracks 372 by means of cables 396 in order to enable selective upward and downward movement of the forward ends of the tracks 372 so as to align the tracks 372 generally parallel with the central axis CC of the drum 212 and place the burner 240 and the device 320 in appropriate alignment for coupling with the heating chamber 230. Dynamic seals 398 are provided between those component parts which rotate with the rotation of the drum 212 and those component parts which remain stationary. In FIG. 3, another apparatus 400 is shown, which is similar in construction and operation to apparatus 200, except that the burner 240 has been replaced by another heating means 402 for providing a source of heat for the volatile organic compound oxidation device 320 and the heating chamber 230. In this instance, the heating means is a heat-cycle operated engine shown in the form of a gas turbine 410, and the exhaust of the gas turbine 410 is coupled at 412 to the volatile organic compound oxidation device 320 to provide the heat necessary to operate apparatus 400. The gas turbine 410 is coupled to a generator 414 for generating electrical power, some of which is used to operate the electric motors 226 which rotate the drum 212. Electric power from generator 414 also is made available for other power requirements at the site of the apparatus. Thus, apparatus 400 not only is self-contained for use at a variety of sites, but provides electrical power at the site. Referring now to FIG. 4, an apparatus which utilizes another auxiliary feature of the present invention in conjunction with a heat circuit which is the subject of US-A-5188299 is illustrated in the form of apparatus 500 which is seen to include an elongate drum 512 having a generally cylindrical wall 514 and an interior 515 extending axially between an inlet end 516 and an outlet end 518. Drum 512 is mounted upon a platform 520 for rotation about a central axis 521 by means of roller assemblies 522 placed on the platform 520 and engaging corresponding circumferential tracks 524 carried by the drum 512, all in a manner similar to that described above in connection with apparatus 200. The drum 512 is inclined at an angle of inclination A so that the inlet end 516 is elevated relative to the outlet end 518. The angle of inclination A is maintained at a relatively shallow acute angle and is adjustable, all as described above in connection with apparatus 200. Heating means is shown in the form of a heating chamber 530 located adjacent the outlet end 518 of the interior 515 of the drum 512 and including a cylindrical side wall 532 which extends along the drum 512 toward the inlet end 516 over a first axial portion of drum 512 from an inlet end 534 of the heating chamber 530 to a front wall 536. A burner 540 is located outside the heating chamber 530 and projects toward the interior 542 of the heating chamber 530 to provide a heating flame 544 projecting toward the interior 542 of the heating chamber 530. A baffle 546 is provided at the front wall 536. A plurality of breaker members in the form of tubular members 550 extend axially, along a second axial portion of drum 512, between the heating chamber 530 and the inlet end 516 of the interior 515 of the drum 512, generally parallel to the central axis 521, and are arrayed circumferentially about the central axis 521. The tubular members 550 are assembled into a cage-like assembly 552 which is supported within the drum 512 in a manner similar to that described in connection with tubular members 50 above, each tubular member 550 having an interior 558 which extends axially along the length of the tubular member 550. Headers in the form of manifolds 560 are integral with the ends of the tubular members 550 adjacent the heating chamber 530, and the manifolds 560 are integral with the front wall 536 of the heating chamber 530 to connect the tubular members 550 with the heating chamber 530. The interior 558 of each tubular member 550 communicates with the interior 542 of the heating chamber 530 through each corresponding manifold 560 so that hot gases in the heating chamber 530 pass through the manifolds 560 and into the tubular members 550. Recyclable asphalt material is received from the field in relatively large pieces 570 fed by an infeed conveyor 572 through the inlet end 516 of the interior 515 of drum 512 and into the cage-like assembly 552 established by the array of tubular members 550. As the drum 512 is rotated, the cage-like assembly 552 also rotates about the central axis 521 and the large pieces 570 are tumbled within the cage-like assembly 552 and simultaneously are broken up and heated by contact with the tubular members 550 of the cage-like assembly 552 as the recyclable asphalt material gravitates downstream from the inlet end 516 toward the outlet end 518 of the interior 515 of drum 512. The circumferential spacing between adjacent tubular members 550 is selected so that upon reaching the desired aggregate-size, the recyclable asphalt material 576 will drop out of the cage-like assembly 552, and fall to wall 514 of the drum 512, all as described above in connection with apparatus 10. The desired aggregate-sized recyclable asphalt material 576 continues down the wall 514 of the drum 512, assisted by flights 580 affixed to the wall 514, until the material 576 reaches the outlet end 518 of the interior 515 of the drum 512. In addition, material 576 is tumbled onto the side wall 532 of the heating chamber 530 where additional heat is transferred to the material 576 and further flights 582 affixed to side wall 532 assist in moving the material 576 downstream. As before, intermediate-sized pieces 588 of recyclable asphalt material which now are smaller than pieces 570, but still remain larger than that which is permitted to fall through the spacing between the tubular members 550, will fall at manifolds 560 to enter the mass of material in the stream 590 of asphalt material leaving the drum 512. The stream 590 of desired aggregate-sized pieces of material 576 is delivered through an exit chute to an outfeed conveyor, as described before. In the preferred configuration, wall 514 of drum 512 is comprised of an inner wall 602 and an outer wall 604, with a heat conduit in the form of an annular heat passage 606 between the inner wall 602 and the outer wall 604. Duct means are provided in the form of return members 608 connected between the end 610 of each tubular member 550 and the annular heat passage 606 so that the heated gases which pass from the heating chamber 530 through the tubular members 550 are directed into the annular heat passage 606 to flow through the wall 514 of the drum 512 and further heat the wall 514 as the heated gases are passed downstream. In this manner heat is conserved and more heat is made available for the process. An insulating jacket 614 extends circumferentially around the drum 512 to further conserve heat, as explained in United States patent US-A-4,932,863. Volatile pollutants which emanate from the recyclable asphalt material as the process is being carried out in the apparatus 500 are dealt with by oxidizing the pollutants in a volatile organic compound oxidation device 620. To that end, the volatile pollutants are conducted from the interior 515 of the drum 512 to the volatile organic compound oxidation device 620 by gas conduction means shown in the form of a manifold 622 located adjacent the outlet end 518 of the interior 515 of the drum 512 and a duct 624 extending between and communicating with the manifold 622, and a plenum chamber 626 extending around the outer periphery of the volatile organic compound oxidation device 620 at the inlet end 628 of the volatile organic compound oxidation device 620. A fan 630 draws the volatile pollutants from the interior 515 of the drum 512, through the manifold 622 and duct 624, and forces the volatile pollutants into the plenum chamber 626, to pass through openings 632 into the volatile organic compound oxidation device 620, all in a manner similar to that described above in connection with apparatus 200. The volatile organic compound oxidation device 620 is interposed between the burner 540 and the heating chamber 530 for operation as described above. As before, cooling means are interposed between the volatile organic compound oxidation device 620 and the heating chamber 530 to reduce selectively the temperature between the outlet 636 of the volatile organic compound oxidation device 620 and the interior 542 of the heating chamber 530 and include a plenum 640 and a blower 644 which forces ambient air into the plenum 640 for distributing ambient air to the interior of the heating chamber 530 to reduce the temperature at the inlet end 534 of the heating chamber 530. When use of the apparatus 500 is to be discontinued, there is a gradual slow-down in production in the drum 512, requiring lowered heat to the tubular members 550; however, full heat must be maintained in the volatile organic compound oxidation device 620 for continued appropriate operation during the transition from full operation to full shut-down. Accordingly, heat is bypassed by the opening of a damper 650 located adjacent the outlet 636 of the volatile organic compound oxidation device 620, which damper 650 is opened to vent excess heat through a by-pass exhaust 654 in order to bypass heat from the volatile organic compound oxidation device 620 away from the heating chamber 530 and thereby protect the component parts of the apparatus 500 against excessively high temperatures during cool down. As a further measure of protection against the effects of excessive heat, it is preferable to construct the heating chamber 530, the manifolds 560 and at least the portions of the tubular members 550 located adjacent the manifolds 560 and the heating chamber 530, of a heat and corrosion resistant alloy, such as stainless steel. A liner 660 of refractory material further protects against excessive heat. The annular heat passage 606, between the inner wall 602 and the outer wall 604 of the drum 512, extends along the drum 512 between the inlet end 516 and the outlet end 518 and is coaxial with the tubular members 550. The heat passage 606 and the interior 588 of the tubular members 550 are connected together serially by the return members 608 such that the heated gases from the interior 542 of the heating chamber 530 are conducted from adjacent the outlet end 518 of the drum 512 to adjacent the inlet end 516 and are returned to adjacent the outlet end 518 serially through the tubular members 550 and the heat passage 606, to be exhausted at an exhaust stack 670, with the aid of an exhaust fan 672. The serial arrangement of the coaxial tubular members 550 and heat passage 606 establishes a heating circuit which enables effective and efficient use of the heat produced by the heating means without exposure of the asphalt material to the hot gases emanating from the heating chamber 530. A spray head 680 is placed within the drum 512, adjacent the inlet end 516, and is connected to a supply 682 of rejuvenating agent or of virgin asphalt for the selective addition of a rejuvenating agent or virgin asphalt. The spray 684 from spray head 680 also serves as a screen tending to reduce dust which otherwise could emanate from the inlet end 516. The effectiveness of the transfer of heat from the heating chamber 530 through the side wall 532 of the heating chamber 530 to the asphalt material moving along the side wall 532 of the heating chamber 530 is enhanced by the particular shape of the flights 582 affixed to the side wall 532 of the heating chamber 530 and contacting the asphalt material. Thus, as best seen in FIG. 5, the flights 582 each have a Y-shaped cross-sectional configuration, including a central stem 690 projecting from the side wall 532 and branches 692 each diverging from the stem 690 at an obtuse angle 694 to the stem 690. The flow of asphalt material in the radial direction is retarded by the branches 692 to enable heat to be transferred to the asphalt material, through the side wall 532 and the flights 582, without unduly impeding the progress of the asphalt material as the asphalt material drops from the flights 582 and gravitates toward outlet end 518, and without fostering an accumulation of asphalt material on the flights 582. The embodiment of the invention illustrated as apparatus 700 in FIG. 6 is somewhat similar to the embodiment described above in connection with apparatus 500 of FIGS. 4 and 5 and, to the extent that similar component parts function in a similar manner, the component parts bear the same reference characters as those employed in connection with the corresponding component parts of apparatus 500. However, in apparatus 700 the circulation of heat from the heating chamber 730 through the tubular members 550 and through the annular heat passage 606 is by the flow of heated gases serially from the heating chamber 730 to the annular heat passage 606 and thence through the tubular members 550 to be exhausted to the stack 670, assisted by exhaust fan 672. Thus, the heat circuit in apparatus 700 operates in a direction opposite to that of the heat circuit in apparatus 500. To this end, an inlet baffle 732 directs heated gases from the heating chamber 730 through an annular outlet 734 to the heat passage 606, and an outlet duct 736 is in position to communicate with the manifolds 560, through a return chamber 738 with which the manifolds 560 are connected for communication between the tubular members 550 and the return chamber 738. Referring now to FIG. 7, another embodiment of the invention is illustrated in the form of apparatus 800 which is seen to include an elongate drum 812 having a generally cylindrical wall 814 and an interior 815 extending axially between an inlet end 816 and an outlet end 818. Drum 812 is mounted upon a platform 820 for rotation about a central axis 821 by means of roller assemblies 822 placed on the platform 820 and engaging corresponding circumferential tracks 824 carried by the drum 812, all in a manner similar to that described above. The drum 812 is inclined so that the inlet end 816 is elevated relative to the outlet end 818. The angle of inclination is maintained relatively shallow and is adjustable, all as described above. Heating means is shown in the form of a heating chamber 830 located adjacent the outlet end 818 the drum 812. A burner 840 is located outside the heating chamber 830 and projects toward the interior 842 of the heating chamber 830 to provide a heating flame 844 projecting toward the interior 842 of the heating chamber 830. A plurality of breaker members in the form of tubular members 850 extend axially along drum 812, between the heating chamber 830 and the inlet end 816 of the interior 815 of the drum 812, generally parallel to the central axis 821, and are arrayed circumferentially about the central axis 821. In this instance, the tubular members 850 are placed around the inside surface 852 of the drum wall 814 and, as best seen in FIG. 8, are each a part of a sheet-like member 854 which extends circumferentially about the inside surface 852 of the drum wall 814. Each tubular member 850 has a generally V-shaped cross-sectional configuration, which includes an apex 856 oriented so that the apex 856 is located radially closest to the central axis 821 of the drum 812, and an interior 858 which extends axially along the length of the tubular member 850. The particular V-shaped cross-sectional configuration of tubular members 850 provides a greater area for the transfer of heat to the asphalt material while, at the same time, enhancing the lifting and movement of the asphalt material along the interior 815 of the drum 812. A heat conduit in the form of a supply heat tube 860 communicates serially with the tubular members 850 through ducting means provided by an end manifold 862 placed between the supply heat tube 860 and the tubular members 850 adjacent the inlet end 816 of the drum 812 and communicates with the heating chamber 842 adjacent the outlet end 818 of the drum 812. Thus, the heat circuit extends serially from the heating chamber 842, through the supply heat tube 860 to the tubular members 850, and thence to the exhaust stack 670, through exhaust fan 672. Recyclable asphalt material is received from the field in relatively large pieces 870 and is fed by an infeed conveyor 872 through the inlet end 816 of the interior 815 of drum 812. As the drum 812 is rotated, the large pieces 870 are tumbled and simultaneously are broken up and heated by contact with the tubular members 850 as the recyclable asphalt material gravitates downstream from the inlet end 816 toward the outlet end 818 of the interior 815 of drum 812. As the recyclable asphalt material 876 continues down the length of the drum 812, the material 876 is tumbled onto the exterior of the supply heat tube 860 where additional heat is transferred to the material 876, and flights 878 affixed to the exterior of supply heat tube 860 assist in moving the material 876 downstream. Volatile pollutants which emanate from the recyclable asphalt material as the process is being carried out in the apparatus 800 are dealt with by oxidizing the pollutants in a volatile organic compound oxidation device 880. To that end, the volatile pollutants are conducted from the interior 815 of the drum 812 to the volatile organic compound oxidation device 880 by gas conduction means shown in the form of a manifold 882 located adjacent the outlet end 818 of the interior 815 of the drum 812 and a duct 884 extending between and communicating with the manifold 882 and a plenum chamber 886. A fan 887 draws the volatile pollutants through the manifold 882 and duct 884, and forces the volatile pollutants into the plenum chamber 886, to pass through openings 888 into the volatile organic compound oxidation device 880, all in a manner similar to that described above in connection with apparatus 200. The volatile organic compound oxidation device 880 is interposed between the burner 840 and the heating chamber 830 for operation as described above. As before, cooling means are interposed between the volatile organic compound oxidation device 880 and the heating chamber 830 to reduce selectively the temperature between the outlet 890 of the volatile organic compound oxidation device 880 and the interior 842 of the heating chamber 830 and include a plenum 892 and a blower 894 which forces ambient air into the plenum 892 for distributing ambient air to the interior of the heating chamber 830 to reduce the temperature at the inlet end 834 of the heating chamber 830. When use of the apparatus 800 is to be discontinued, heat is bypassed by the opening of a damper 896, as described above. The employment of sheet-like members 854 enables ready replacement of the tubular members 850 as necessary during the life of apparatus 800. Since it is the tubular members 850 which are exposed to the most severe heat and wear conditions during operation of the apparatus 800, the apparatus is made more economical by enabling ready replacement of the tubular members 850, as necessary. To this end, the sheet-like members 854 are in the form of segments 900 fastened in place by selectively removable fasteners, shown in the form of bolts 910. When the tubular members 850 become worn and require replacement, bolts 910 are unfastened to release segments 900 of the sheet-like members 854 for removal and replacement. As depicted in FIG. 8, the flights 878 on the supply heat tube 860 have a cross-sectional configuration similar to that of the tubular members 850, thereby providing some supplemental breaking function to assist in breaking down the larger pieces of asphalt material gravitating along the supply heat tube 860, as well as enhancing the transfer of heat to the asphalt material, and the lifting and movement of the asphalt material along the interior 815 of the drum 812. However, as best seen in FIG. 9, an alternate construction provides alternate flights 920 having a Y-shaped cross-sectional configuration for effective transfer of heat to the asphalt material, as described above in connection with flights 582. The embodiment of the invention illustrated as apparatus 1400 in FIG. 10 is somewhat similar to the embodiment described above in connection with apparatus 800 of FIG. 7 and, to the extent that similar component parts function in a similar manner, the component parts bear the same reference characters as those employed in connection with the corresponding component parts of apparatus 800. However, in apparatus 1400, the inclination of the drum 1412 is in a direction opposite to that of apparatus 800, so that the inlet and outlet ends of the drum are reversed. Thus, in apparatus 1400, the inlet end 1416 is adjacent the heating means, while the outlet end 1418 is adjacent the end of the drum 1412 opposite the heating means. Recyclable asphalt material is received from the field and is fed into apparatus 1400 by an infeed conveyor 1420 through the inlet end 1416 of the drum 1412. The asphalt material gravitates from the inlet end 1416 to the outlet end 1418 where the processed material is discharged for delivery at 1430. It will be seen that the present invention attains the objects and advantages summarized above, namely: Eliminates the need for preliminary crushing and screening of recyclable asphalt materials received from the field, and the equipment needed for such preliminary crushing and screening precludes direct contact between the recyclable asphalt materials and any open flame or hot gases thereby eliminating a potential source of pollutants, and especially "blue-smoke" and hydrocarbon emissions; effectively recycles used asphalt materials for use either in a mix containing a very high percentage of recycled product with virgin aggregate and asphalt or one-hundred percent recycled materials; provides apparatus which is relatively compact and even more portable than before for ready transportation and use directly at a wider variety of project sites; enables increased versatility in complementing existing asphalt plants for the use of recycled asphalt product; provides an environmentally sound approach to the conservation of asphalt products at minimal cost; eliminates the need for disposal of used asphalt materials; effectively deals with pollutants which emanate from the asphalt materials being processed for reuse; enables the practical processing of recyclable asphalt materials for widespread use with efficiency and reliability. It is to be understood that the above detailed description of preferred embodiments of the invention are provided by way of example only. Various details of design, construction and procedure may be modified without departing from the true scope of the invention as set forth in the appended claims.

Claims: Apparatus for processing recyclable asphalt material received from the field in relatively large pieces (570) for delivery in a mass containing desired smaller aggregate-sized pieces (576) for reuse, wherein the apparatus includes an elongate drum (512) having a generally cylindrical wall (514), a central axis (521), a first end (518) and a second end (516), mounting means (522, 524) for mounting the drum (512) for rotation about the central axis (521), with the central axis (521) tilted at an acute angle (A) so as to elevate one of the first and second ends (518, 516) relative to the other of the first and second ends (518, 516), a heating chamber (730) adjacent the first end (518) of the drum (512), the heating chamber (730) having an interior (542), a plurality of breaker members (550), the breaker members (550) being tubular and extending along the drum (512) between the first and second ends (518, 516) of the drum (512), the breaker members (550) being arrayed generally parallel to the central axis (521) and placed between the central axis (521) and the wall (514) of the drum (512), a heat conduit (606) extending along the drum (512) between the first and second ends (518, 516) of the drum (512), the heat conduit (606) being coaxial with the breaker members (550), heating means (540) for supplying heat to the interior (542) of the heating chamber (730), ducting means (608) interconnecting the interior (542) of the heating chamber (730), the breaker members (550), and the heat conduit (606) such that heat from the interior (542) of the heating chamber (730) is conducted from adjacent the first end (518) of the drum (512) to adjacent the second end (516) of the drum (512) and is returned to adjacent the first end (518) of the drum (512) through the breaker members (550) and the heat conduit (606), feed means (572) for feeding the large pieces (570) of recyclable asphalt material received from the field into the drum (512), adjacent the elevated one of the first and second ends (518, 516) of the drum (512), and rotational means (226) for rotating the drum (512), the breaker members (550) and the heat conduit (606) about the central axis (521) so as to tumble the large pieces (570) of recyclable asphalt within the drum (512), against the breaker members (550) and against the heat conduit (606), thereby simultaneously reducing the size of the relatively large pieces (570) to the desired aggregate-sized pieces (576) and heating the mass (290) containing the desired aggregate-sized pieces (576), which mass (290) proceeds toward the other of the first and second ends (518, 516) of the drum (512) for delivery from the drum (512), characterized in that the heating chamber (730) communicates with the heat conduit (606) adjacent the first end (518) of the drum (512) and the breaker members (550) communicate with the heat conduit (606) adjacent the second end (516) of the drum (512), such that the heat is conducted serially from the heating chamber (730), through the heat conduit (606) and then through the breaker members (550) to be exhausted from the breaker members (550) adjacent the first end (518) of the drum (512). An apparatus according to claim 1, wherein the first end (1416) of the drum (1412) is elevated relative to the second end (1418) of the drum (1412), the feed means (1420) feeds large pieces (570) of recyclable asphalt material into the drum (1412) adjacent the first end (1416) of the drum (1412), and the mass (290) containing the desired aggregate-sized pieces (576) is delivered from the drum (1412) adjacent the second end (1418) of the drum (1412). An apparatus according to claim 1, wherein the second end (516) of the drum (512) is elevated relative to the first end (518) of the drum (512), the feed means (572) feeds the large pieces (570) of recyclable asphalt material into the drum (512) adjacent second end (516) of the drum (512), and the mass (290) containing the desired aggregate-sized pieces (576) is delivered from the drum (512) adjacent the first end (518) of the drum (512). An apparatus according to claim 1, wherein the breaker members (850) lie in a sheet-like member (854) extending circumferentially along at least a portion of the inner surface (852) of the cylindrical wall (814) of the drum (812), and the apparatus includes selective fastener means (910) for selectively fastening the sheet-like member (854) in place along said portion of the inner surface (852) of the cylindrical wall (814) of the drum (812) and selectively releasing the sheet-like member (854) from said portion of the inner surface (852) of the cylindrical wall (814) of the drum (812). An apparatus according to any one of claims 1 to 4, wherein at least some of the breaker members (850) have a generally V-shaped cross-sectional configuration including an apex (856), with the V-shaped cross-sectional configuration oriented such that the apex (856) is radially closest to the central axis (821) of the drum (812). An apparatus according to any one of claims 1 to 5, wherein the heat conduit (858) is located between the inner surface (852) and the outer surface of the cylindrical wall (814) of the drum (812). An apparatus according to any one of claims 1 to 5, wherein the heat conduit (860) is located along the central axis (821) of the drum (812). An apparatus according to any one of claims 1 to 5, including flights (878) along the heat conduit (860) for assisting movement of the mass (290) of asphalt material along the drum (812). An apparatus according to claim 8, wherein the flights (878) have a Y-shaped cross-sectional configuration, the Y-shaped cross-sectional configuration including a stem (690) projecting from the heat conduit (860), and branches (692) extending from the stem (690), at an obtuse angle (694) to the stem (690). An apparatus according to any preceding claim, including selectively detachable coupling means (370) coupling the heating means (240) with the interior (242) of the heating chamber (230). An apparatus according to claim 10, wherein the selectively detachable coupling means (370) includes translation means (372) for enabling selective translation of the heating means (240) essentially parallel to the central axis (CC) of the drum (212), toward and away from the drum (212) for corresponding selective coupling and uncoupling of the heating means (240) and the interior (242) of the heating chamber (230). An apparatus according to claim 11, wherein the heating means (240) and the selectively detachable coupling means (370) are located adjacent the outlet end (218) of the interior (215) of the drum (212). An apparatus according to any preceding claim, including: volatile organic compound oxidation means (320) interposed between the heating means (240) and the heating chamber (230), the volatile organic compound oxidation means (320) having an inlet (328) and an outlet (336), the inlet (328) communicating with the heating means (240) and the outlet (336) communication with the heating chamber (230); and gas conduction means (324) interconnecting the interior (215) of the drum (212) with the inlet (328) for the volatile organic compound oxidation means (320) for conducting pollutants from the interior (215) of the drum (212) to the volatile organic compound oxidation means (320); whereby the pollutants conducted to the volatile organic compound oxidation means (320) are oxidized in response to heat supplied by the heating means (240). An apparatus according to claim 13, wherein the gas conduction means (324) interconnects the interior (215) of the drum (212) adjacent the outlet end (218) of the interior (215) of the drum (212) with the inlet (328) of the volatile organic compound oxidation means (320). An apparatus according to claim 14, including cooling means (340) interposed between the outlet (336) of the volatile organic compound oxidation means (320) and the heating chamber (230) for reducing the temperature between the outlet (336) of the volatile organic compound oxidation means (320) and the interior (242) of the heating chamber (230). An apparatus according to claim 15, wherein the cooling means (340) includes air distribution means (342) for distributing ambient air between the outlet (336) of the volatile organic compound oxidation means (320) and the interior (242) of the heating chamber (230). An apparatus according to claim 16, wherein the volatile organic compound oxidation means (320) includes an outer periphery at the inlet (328) of the volatile organic compound oxidation means (320), and gas distribution means (326) at the inlet (328) of the volatile organic compound oxidation means (320) for distributing the pollutants conducted by the gas conduction means (324) along the outer periphery at the inlet (328) of the volatile organic compound oxidation means (320). An apparatus according to claim 17, wherein the gas conduction means (324) interconnects the interior (215) of the drum (212) adjacent the outlet end (218) of the drum (212) with the inlet (328) of the volatile organic compound oxidation means (320). An apparatus according to any preceding claim, including residual emission collection means (360) adjacent the inlet end (216) of the interior (215) of the drum (212). An apparatus according to any preceding claim, wherein the rotational means (226) include electric motor means (226) coupled with the drum (212) for rotating the drum (212), and the heating means (402) comprises a heat-cycle operated engine (410) having a heated exhaust for supplying heat to the interior (242) of the heating chamber (230), and an electric power generator (414) operated by the engine (410) for supplying power to the electric motor means (226). An apparatus according to any preceding claim, wherein the heating means (402) comprises a heat-cycle operated engine (410) having a heated exhaust for supplying heat to the interior (242) of the heating chamber (230) and an electric power generator (414) operated by the engine (410) for supplying electric power to the site where the apparatus is located. An apparatus according to claim 21, wherein the rotational means (226) includes electric motor means (226) coupled with the drum (212) for rotating the drum (212), and the electric power generator (414) supplies electric power to the electric motor means (226). An apparatus according to claim 20, 21 or 22, wherein the engine (410) comprises a gas turbine (410).

Inventors: ANDERSON RUSSELL W, HANLON LAWRENCE C, HENDRICKSON ARTHUR N, ANDERSON, RUSSELL W, HANLON, LAWRENCE C, HENDRICKSON, ARTHUR N
Applicants: RAP PROCESS MACHINERY CORP, RAP PROCESS MACHINERY CORP.
Application year: 1994
Main classification: E01C19
IPC codes: E01C19